This cylindrical, 2.13" x 0.98" x 0.98" gearmotor uses a brushed DC motor with extra-strong magnets and a 98.78:1 metal gearbox to deliver a lot of power in a relatively small package. These units have a 0.315"-long, 4 mm-diameter D-shaped output shaft. We also carry a lower-power version of this gearmotor and a version with an encoder.